Process for the conversion of gas produced by pressure gasification



United States Patent Ofifice 3,069,250 PROCESS FOR THE CONVERSION OF GAS PRO- DUCED BY PRESSURE GASIFICATION Hellmuth Weitt-enhiller, Essen-Bredeney, Franz Bieger,

Dorsten, Harry Schofl, Essen-Margarethenhohe, Wilhelm Herbert, Frankfurt am Main, Oskar Dorschner, Bad Homburg-Gonzenheim, and Hans Werner Gross, Buchschlag, Kreis Ofienbach, Germany, assignors to Metallgesellschaft Aktiengesellschaft, Frankfurt am Main, Germany, a German corporation No Drawing. Filed June 6, 1960, Ser. No. 33,956

Claims priority, application Germany June 9, 1959 13 Claims. (Cl. 48-197) This invention relates to improved gaseous fuels applicable for industrial and residential use by both municipal and long-distance distribution and, more particularly, relates to a process by which long-distance fuel gas may be produced from crude fuel gases having a relatively high content of carbon monoxide and other impurities, and which have been pro-treated to remove only that part of these impurities which is injurious to the conversion catalyst.

By subjecting carbon-containing liquid or solid fuels, such as coal or mixtures thereof, to oxygen or oxygencontaining gases and steam treatment under pressure, gaseous fuel products which are suitable for industrial or residential purposes may be recovered. The gas produced in the pressure treatment generally has a relatively high content of carbon dioxide of about 25-30%. Upon reducing the undesirable carbon dioxide present to a content of only about 2% by volume by scrubbing techniques, the heating value of the resulting fuel gas is between 3700 and 45 kcal. per m. depending on the particular fuel originally charged. The density of the gaseous fuels after scrubbing to remove carbon dioxide is higher than that of coke-oven gas.

The carbon monoxide content of these pressure-formed gases can be varied between the range of about 18 and 40% by volume, depending on the quantity of steam used in the gas formation. Generally, the higher the rate of steam addition, the lower will be the carbon monoxide content. A large addition of steam during the pressure gasification can, however, render the method most uneconomical, in that, when large quantities of steam are added, the gasification temperatures are relatively low and the conversion is not extensively effected. Additionally, where a large quantity of fresh steam is added to the reaction zone, the solid fuel ash does not sinter, but accumulates as a powder instead, which can only be removed with great difiiculty from the ash sluice.

It is an object of this invention to provide a process for the production of a fuel gas low in carbon monoxide and substantially free from undesirable impurities, which may be admixed with gases having higher calorific values to form a long-distance fuel gas.

It is a further object of the invention to provide a process for the production of a fuel gas with a desirably low carbon monoxide content under technically and economically favorable reaction conditions, which gas can then be admixed with gases having higher calorific values to form a mixture having the calorific value necessary for long-distance fuel gas, without exceeding the density of coke-oven gas.

It is a still further object of the invention to provide a process for the production of a fuel gas low in carbon monoxide and substantially free from other undesirable impurities without sacrificing the major portion of the oil and tar components of the gas by conversion of a gas produced by pressure gasification, which can thereafter, by the addition of certain gases thereto, have the calorific value of the mixed gas increased considerably without thereby exceeding the density of coke-oven gas.

Other and further objects will become apparent from the study of the within specification.

It is already known that both crude gases containing high-boiling hydrocarbons, tars and pitches as well as gases which have been freed to a great extent from the high-boiling hydrocarbons, tars and pitches and which have been obtained by a gasification reaction effected without pressure, can be converted with steam in the presence of suitable, non-sensitive catalysts to produce a gas with richer combustibles content. However, the catalysts, whose activity is not strongly diminished, i.e. which are only slightly sensitive to contact with crude gases containing high-boiling hydrocarbons, tars and pitches, are characterized in that, in the presence of the high carbon dioxide content of the pressure-generated gas, they effect an insufficient transformation of the gas during the conversion.

Furthermore, it has been found that even slightly sensitive catalysts, when the conversion reaction is carried out under pressure, allow only low volumetric velocities and have a very limited life with respect to duration of activity.

It has now been discovered that this failure of the catalyst to give desirable conversion yields is due to the fact that the pressure gasification gas contains substances which considerably reduce or completely destroy the activity of the conversion catalyst. These substances are in particular reactive asphalt materials, such as unstable tar components, resin-forming impurities, carbon dioxide, hydrogen sulfide, organic sulfur compounds, ammonia, hydrocyanic acid, as well as such compounds as styrol, diolefins, nitric oxide, etc.

According to the invention, the crude hot-pressuregenerated gas, substantially at the pressure of the gasification, may be treated to remove a portion of these solid, liquid and resin-forming attendant impurities in such a manner that the major portion of the oil and tar components, which do not injuriously afiect the catalyst, remain in the gas. The conversion of the partially purified crude gas is then carried out under pressure in the presence of a conversion catalyst, wherein the unused steam present is utilized to produce a richer combustible content. The converted gas is thereafter cooled and purified in any known manner.

Under these circumstances, not only can the pressure conversion of the gas be carried out without impairing, and thereby diminishing the activity, of the catalysts, but it is possible at the same time to improve the hydrocarbon, oil and tar constituents remaining in the gas. The steam content and the vaporous oil and tar constituents of the gas can be increased by adding water, steam or oil to 'the gas before it reaches the conversion stage. At the same time it is possible to use any unused steam and additionally the heat which is contained in the crude gas, so that little or no steam or heat is wasted in the overall process, thereby decreasing the cost of con-' ducting the same.

The partial purification and removal from the hot crude gas on its exit from the pressure gasification zone of the disturbing and interfering substances, which not only detrimentally affect the catalysts but also form 'incrustations and deposits on the walls of the heat-exchanger and water with oil and/or tar, whereby the gas is cooled and Patented Dec. 18, 1962 its content of vapors of water and/ or oil 'and/ or tar is increased. The gas is now cooled further to such an extent that the condensates separate out in the desired quantities. By this cooling, the high-boiling products, resinforming impurities and dust, including tars and oil droplets, are separated out in the condensate, all of which may be removed therefrom, as for example by suitable cyclone means. Any mist and/or liquid droplets still remaining in the gas can be removed from the gas by such known means as baffie separators, filters or the like. The deposits and incrustations on the walls of the heater are caused chiefly by the cracking of the mist and liquid droplets which were permitted to remain in the gas and to settle out on the walls of the heater. In order to further ensure against such formations, the baffle separators and filters can be heated to temperatures at which the mist and liquid formation can no longer take place. The cooled, crude gas, purified in this manner, is then reheated, as for example via suitable heat-exchange means, by the hot pure gases emanating from the subsequent conversion and brought to the conversion temperature. In this process, any cooling of the gas between the filter and heater, which might again lead to the formation of mist and liquid droplets in the gas, is carefully avoided.

The condensate formed from the gas, enriched with steam, can be conducted through conventional waste heatstearn boilers or similar heat exchangers, and the concentrate thereby recovered can be used as washing liquid. The high-boiling oil and petroleum fractions are preferably returned into the gasification reaction zone in order to form therein as the upper layers thereof a filter layer on the solid fuel wetted by these substances and preventing the entrainment of any solid fuel particles, because the same, being a wetted loose layer, has a filtering effect. Further in this manner, the interfering impurities are at the same time partially destroyed in the gasification zone.

If the hot gas is treated by washing with an oil or tar, an increase in its content of oil and tar vapors takes place. At the same time, when the gas is treated by washing with an oil or tar, a more or less extensive cooling of the gas is brought about. As the oil and tar washing mixtures effect a particularly extensive removal of the impurities, i.e. disturbing substances, from the gas, it is not necessary to cool the gas exiting from the pressure gasification zone to the low temperatures which are required when aqueous liquids are employed as washing agents to separate out the high-boiling, resin-forming impurities which may be present. The advantage is thereby attained that the gas, after being washed with an oil or tar,

or mixture thereof, can be conducted at a suitably high temperature through the bafile separator or filter into the conversion reaction stage without the vaporous oils and/ or tars being condensed out and with only small quantities of tar condensate being separated out. The heat-exchange means-for reheating the gas to the temperature required for the conversion becomes entirely or partially superfluous, which represents a considerable advantage of this embodiment of the invention.

The extent to which the partial separation of the disturbing impurities is effected is regulated according to the extent to which the vaporous tar and oil gas components are or are not injurious to the conversion catalyst over a relatively long period of time. On account of the improvement resuling from the hydrocarbons remaining in or added to the gas, it is advantageous to limit as far as possible the quantity of components which are separated out.

It has also been found in accordance with the invention that the quantity of substances separated out can be lowered if care is taken to eliminate any possible formation of the very fine separated droplets of oil and tars. Consequently, it is advantageous to employ as separator, i.e. cyclone, etc., an arrangement having a high degree of efficiency.

After limited partial separation of the disturbing substances by cooling and removal thereof, the crude gas is reheated to the temperature, as for example via suitable heat-exchange means, which is required for the conversion.

These hot gases are then conducted over a conversion catalyst in a conversion reaction zone to convert a substantial part of the carbon monoxide present with a stoichiometric quantity of the unused steam present to carbon dioxide and hydrogen. In this way, little or no steam is wasted in the overall process, and the quantity of gas liquors from which water must be recovered is decreased, thereby decreasing the cost of such water recovery.

Surprisingly, this conversion takes place at conditions almost completely corresponding to those of equilibrium, in spite of the impurities contained in the crude gas, such as carbon dioxide, hydrogen sulfide, organic sulfur compounds, ammonia, hydrocyanic acid, resin-forming impurities and the like, which are recognized catalyst poisons.

According to another embodiment of the invention, the attendant impurities, which impair the activity of the conversion catalyst, are removed from the gas employing therefor surface-active substances, such as coals and cokes having sufficient surface activity, silica gel, active argillaceous earth or by fission catalysts such as chromium oxide catalysts on active carrier substances. In this embodiment, a cooling agent, such as oil, tar or water or steam, is introduced into the hot crude gas by suitable injection means in such quantity that the temperature of the crude gas leaving the pressure gasification zone is only reduced to that value which is suitable for the conversion reaction without any considerable separation first taking place by the condensation of high-boiling tar or pitch constituents. The introduction of any cooling agent can be dispensed with if the gas coming from the gas generator is already at the conversion temperature.

The removal of the disturbing substances is then eflfected by using the surface-active solid substances, which possess the property of holding the disturbing substances on their surface, or converting them into harmless compounds. These surface-active materials can at the same time have a certain catalytic effect in the sense of the conversion reaction to be effected. The determining factor in their selection is, however, their lasting effectiveness for removing the disturbing substances or their being capable of regeneration in an easy and simple manner, for example by oxidation of the disturbing substances collected on their surfaces with gases containing oxygen.

The surface-active substances are used in heaped-up fixed-bed form or as a fluidized bed, in which the crude gas to be purified or, during the period of regeneration, the gases containing oxygen constitute the suspension gas. The surface-active substances can additionally also be guided in circulation between two reaction chambers, in the first of which they effect the removal of the disturbing substances from the crude gas, after which they are then conducted into the second reaction chamber to be regenerated, after which they are returned to the first reaction chamber.

After the disturbing substances have been separated out by the surface-active materials, the preliminarily cleansed gas is also filtered, if necessary, in order to remove any particles separated from the surface-actve materials, and then passed directly to the conversion reaction stage. The gas contains a large quantity of carbonic acid as well as carbon monoxide, hydrogen sulfide, organic sulfur compounds, ammonia and hydrocyanic acid, and tar vapors, that is, all components of the crude gas, with the exception of the disturbing substances, resinified or held by the surface-active solid substances as well as, in the case where steam is introduced, an increased steam content as compared with the crude gas. As has already been mentioned, the gas is at conversion temperature. By carrying out the conversion reaction following the pre-treatment of the I l l x s The pretreatment allows the use also of very active conversion catalysts, whose activity can be mainta ned for a very long period of time with a high volumetric velocity of about 500 to 2500 m? of gas, preferably 700 to 1000 'in the benzine increase considerably, the olefin content drops and the content of saturated hydrocarbons rises. At the same time, the content of water-soluble phenols increases. Moreover, the content of sulfur compounds in both the oil and tar decreases. The content of acid oils in the light and medium oils is also considerably lessened, which shows that the higher molecular, less desirable phenol constituents have been converted into water-soluble phenols. In the gas itself, the hydrocyanic acid content and the content of organic sulfur compounds have diminished to fractional parts of that which they were originally.

It has also been found that the partial cleaning of the crude gas, according to the invention, likewise allows advantageously the use of conversion catalysts which at the same time have a hydrogenating effect and further contribute to the improvement of the oil and tar constituents of the crude gas. This can be carried so far that the light ends obtained during the preparation of the gas after the conversion reaction require no further finishing by, for example, hydrogenating refining, but whereby a motor fuel is obtained directly solely by distillation separation from the light and medium oils and, if necessary, washing out the phenols. p The catalytic conversion may be carried out, employing as conversion catalyst, for example, iron oxide catalysts activated with chromium oxide. However, other less expensive materials may be used advantageously, such as bog iron ores or similar iron oxide hydrates. In place of iron oxide catalysts, catalysts containing oxides or sulfides of metals of the 6th group of the periodic system, particularly molybdenum and tungsten as effective metal, may be used with good results. These catalysts have at the same time a more or less distinct hydrating effect, especially when they are admixed with sulfides or oxides of metals of the 8th group of the periodic system, such as cobalt or nickel. A catalyst formed of active alumina with 3.4% cobaltous oxide and 9.6% molybdenum trioxide has, for example proved highly suitable.

The two embodiments for preliminary purification according to the invention can also be used jointly. This is advantageous, for example, when, by partial separation of the high-boiling tar or pitch components by cooling, the disturbing tar constituents of the crude gas have been removed, but not the other interfering and disturbing substances, such as styrol, diolefins or nitric oxide, which are present in the gas and which may occur alone or jointly in the resinification reactions which attack the conversion catalyst and considerably impair its high activity. In this instance, the treatment described with surface-active solid substances is carried out after the partial separation of the high boiling tar or pitch constituents by cooling before or after the gases have been heated to conversion temperature, and only thereafter is the gas conducted over the conversion catalyst.

It has also proved advantageous, before treating the gas with surface-active substances in the preliminary cleaning operation, to introduce again and vaporize the whole or a portion of the tar constituents obtained from the gas in refined state after the conversion reaction, for example, in fractions, possibly also with aqueous concentrates, at those points where a cooling of the gases occurs for the partial separation of the high-boiling tar and pitch constituents or for attaining the conversion temperature. In this manner, the tar constituents capable of being improved 6 are subjected several times to the refining action of the conversion catalyst, and the quality of the refined products is improved.

In addition, inherent or foreign hydrocarbons, for example mixtures of water and hydrocarbons, can be introduced for vaporization and conversion by the catalyst at any point between the gas outlet from the pressure gas generator and the gas inlet to the catalyst, providing these hydrocarbons do not come into contact with the catalyst in the form of droplets, but only in vaporous state. By this measure, liquid or solid disturbing substances are reliably prevented from reaching the catalyst and thereby causing damage. At the same time and under all circumstances, it is important that the arrangement be such that also in the heating devices thermic decomposition of the hydrocarbons or the like, contained in the gas, cannot take place. Therefore, it is advisable to introduce the heating medium into the heating devices in counter-flow to the gas.

After leaving the conversion reaction zone, the converted gas may be cooled through heat-exchange means, releasing the major part of its heat to the gas entering the conversion reaction zone and its residual heat through heat-exhange means to a waste heat boiler for the production of steam. Thereafter, direct or indirect cooling means may be employed for final cooling of the gas freed from carbon dioxide and hydrogen sulfide, as for example by suitable conventional scrubbing techniques. Upon drying, the purified gas may be used as a synthesis gas or directly as an industrial or residential gas via longdistance or local distribution.

The purified gas obtained in accordance with the process of the invention normally contains only about 4 to 8% carbon monoxide, and its tensity is ordinarily below that of coke-oven gas. However, if desired, for specific purposes the gas may be made to have a higher carbon monoxide content than 8% and a higher density as well by effecting a less complete transformation in the conversion reaction zone or by mixing non-converted gas with the purified converted gas.

The advantage of the process in accordance with the invention is increased by the advantages resulting fromthe use of the converted gas thereby obtained. The pressure-produced gas obtained, for example, from pit coal has a calorific value below 4000 kcal. per in. after the separation of the carbon dioxide. To increase this, it can be mixed with natural gas, but then the density rises above that of the coke-oven gas. This, however, hinders or prevents the use of the mixed gas for long-distance gas supply. If, on the other hand, the pressure-produced gas is converted and completely or partially freed from carbon dioxide, its density drops considerably. Therefore, by adding gases having a high calorific value, such as for example natural gas, refinery gas, propane, butane, it can easily be brought to the calorific value necessary for longdistance gas supply, for example 4600 kcal. per m. without exceeding the density of coke-oven gas. By this measure, breakdowns in manufacturing works, using longdistance supply gas and the burners of which frequently,

react very sensitively, are avoided. Furthermore, the density of the gas produced can be adjusted by the addition of other gases having a higher density, such as nitrogen, carbon dioxide, flue gases or the like.

Also, the pressure gasification itself can be performed in a very favorable manner according to the instant invention. The carbon monoxide content of the pressure-generated gas can, as is known, be varied between about 10 and 40% of the pure gas, inthat the gasification of the fuel is carried out with larger or smaller quantities of steam. It is now possible, according to the invention, to work advantageously with a small addition of steam and thus already obtain considerable economic advantages. But also for technical reasons, this smaller addition of steam is of importance, because, even in the case ofdiflL, cult fuels, it produces an ash which is light and easy to The gas generator is operated under a pressure of 23 atmospheres and with oxygen and steam in the ratio of about 1. m. oxygen:4.5-6.5 kgs. of steam as gasifying agents. The gas thus obtained leaves the gas generator in the case of open-burning coal at a temperature of about 500600 C. It is cooled in a washing cooler to a temperature of about 190-210 C., preferably 195-200 C., whereby any liquid produced in the cooling process, as for example aqueous condensate, is advantageously used as washing agent. High-boiling products and dust, in cluding pitch, tar and oil droplets, separate out in the washing cooler. The gas takes up the water from the washing agent in the form of vapor. The water absorbed depends upon the temperature conditions and the dew point of the gas entering the washing cooler. The gas passes into the washing cooler with a dew point of, for example, 178 C. and leaves the washing cooler with a dew point of about 195 C. The gas can be further cooled to a temperature of about 160-l70 C. in a wasteheat boiler, whereby an aqueous condensate is produced which contains considerable quantities of nitrogen. The condensate is advantageously circulated as Washing agent through the Washing cooler. On leaving the Waste-heat boiler, the gas has the following composition, based on dry gas:

Percent CO 26.5 C 23 H 39 CH; N 1 H 8 0.5

that in spite of a high CO and water vapor content a change in the condensable and gaseous hydrocarbons takes place, in that the gas-benzine is about doubled and the quantity of aromatic substances contained therein increased considerably, being in many cases doubled, with the result that the density of the gas-benzine is greater, the bromine number dropping to about A of the original value, as for example from 47 to 12, and the olefin content dropping correspondingly, as for example from by volume to 6% by volume. The content of saturated hydrocarbons is increased, as for example from 12% by volume to 29% by volume. The content of water-soluble phenols is increased, as for example from 2 g. per liter to 10 g. per liter, and also the total sulfur content of the gas-benzine is decreased, as for example from 0.81% by weight to 0.15% by weight.

After the conversion reaction, the gas-benzine is recovered in the known manner, as for example by a washing with oil after high-boiling benzine and oil constituents, which are contained in the converted gas, have been separated out by condensation. These are specifically lighter after passing through the catalyst than they were before. Their content of acid oils is considerably less, as for example decreased from 36% by volume to 13% by volume. The sulfur content has dropped similarly to the gaS-benzine content. At .the same time, the content of liydrocyanic acid of the gas is decreased, as for example from to 4 mg./rn. and the content of organically bound sulfur is decreased, for example, from 300 to 25 mg./m.

In addition, it is important for the procedure in accordance with the invention that the gas throughput can be between about 500 and 2500 m. of gas per m9 of catalyst an hour and that the process is conducted at catalyst temperatures of about 240-660 C., preferably 400- 500 C.

Example 2 The production of a standard, long-distance supply gas, starting with a pressure-produced gas converted according to the process of the invention, takes place as follows:

The converted gas employed has, for example, a carbon monoxide content of 6%. Its density, after the carbon dioxide has been washed out to a residue content of, for example, 23%, amounts to about 0.25 to 0.3, relative to air=1. 2580 111. of this converted pressure-produced gas, which, after cleaning to 3% carbon dioxide, consists of 1670 m3 pure gas, are mixed with 860 m. of natural gas and 500 m. of nitrogen to form 3030 m. of standard long-distance supply gas.

We claim:

1. Process for the production of a purified fuel gas having a low carbon monoxide content from hot crude fuel gas high in carbon monoxide and attendant impurities obtained by pressure gasification of solid carbon-containing fuels with steam and oxygen, which comprises cooling said hot crude gas to a temperature of about to 210 C. by contacting the hot crude gas under pressure with a member selected from the group consisting of steam, oil, tar, and mixtures thereof, whereby the high boiling products, reactive asphaltic materials, resin-forming impurities, water, tars, pitches, and like materials form a condensate, conducting the crude gas after separation therefrom of said condensate at the conversion temperature and at substantially the same pressure as the pressure of the starting hot crude gas over a conversion catalyst to thereby convert the high content of carbon monoxide and steam un used in the pressure gasification contained in said crude gas to carbon dioxide and hydrogen, and thereafter recovering the low carbon monoxide content fuel gas.

2. Process according to claim 1, which comprises heating said crude gas after removal of the condensate therefrom to said conversion temperature prior to conducting the crude gas over said conversion catalyst.

3. Process according to claim 2, wherein the heat of the gas recovered from the conversion is utilized to effect said heating of said crude gas.

4. Process according to claim 1, which comprises recycling said condensate to said pressure gasification.

5. Process according to claim 4, which comprises employing said condensate as a wetting agent for said solid fuel to be gasified.

6. Process according to claim 1, in which said conversion catalyst additionally exerts a hydrogenating effect.

7. Process according to claim 1, wherein said crude gas is conducted over said conversion catalyst at a throughput rate of from 500 to 2500 m. per m. catalyst an hour.

8. Process for the production of a purified fuel gas having a low carbon monoxide content from hot crude fuel gas high in carbon monoxide and attendant impurities obtained by pressure gasification of solid carbon-contain ing fuels with steam and oxygen, which comprises cooling said hot crude gas to the temperature required for the conversion of the carbon monoxide and steam content in said crude gas to carbon dioxide and hydrogen by contacting the hot crude gas under pressure with a member selected from the group consisting of steam, oil, tar, and mixtures thereof, thereafter passing said partially cooled crude gas in contact with a surface-active solid substance capable of removing the high boiling products, reactive asphaltic materials, resin-forming impurities, water, tars,

pitches, and like materials present in said gas, conducting the crude gas after separation therefrom of said materials at the conversion temperature and at substantially the same pressure as the pressure of the starting hot crude gas over a conversion catalyst to thereby convert the high content of carbon monoxide and steam unused in the pressure gasification contained in said crude gas to carbon dioxide and hydrogen, and thereafter recovering the low carbon monoxide content fuel gas.

9. Process according to claim 8, wherein said surfaceactive solid substance is a member selected from the group consisting of surface-active carbons, silica gels, argillaceous earths, and fission catalysts.

10. Process according to claim 8, wherein said contacting with said solid surface-active substance is eifected at a temperature of between 240 and 660 C.

11. Process for reproducing long-distance fuel gas, which comprises cooling hot crude fuel gas high in carbon monoxide and attendant impurities obtained by pressure gasification of solid carbon-containing fuels with steam and oxygen to a temperature of 190 to 210 C. by contacting the same under pressure with a member selected from the group consisting of steam, oil, tar, and mixtures thereof, whereby the high boiling products, reactive asphaltic materials, resin-forming impurities, Water, tars, pitches, and like materials form a condensate, conducting the crude gas after separation therefrom of said condensate at the conversion temperature and at substantially the same pressure as the pressure of the starting hot crude gas over a conversion catalyst to thereby convert the high content of carbon monoxide and steam unused in the pressure gasification contained in said crude gas to carbon dioxide and hydrogen, recovering the low carbon monoxide content fuel gas, thereafter cooling and scrubbing the converted gas to remove therefrom further impurities such as hydrogen sulfide, organic sulfur compounds, ammonia, hydrocy-anic acid and nitric acid, admixing said purified gas with gases having higher calorific values than such purified gas to thereby form a long-distance fuel gas having a condensate below that of coke oven gas.

12. Process according to claim 11, wherein said gas having a high calorific value is a member selected from the group consisting of natural gas, a refinery gas, propane, butane and mixtures thereof.

13. Process according to claim 12, which comprises additionally adding to said purified gas a member selected from the group consisting of nitrogen, carbon dioxide, flue gas and mixtures thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,918,254 Faber July 18, 1933 1,926,170 Oberfell et al Sept. 12, 1933 2,134,548 D-anulat Oct. 25, 1938 2,671,718 De Coriolis Mar. 9, 1954 FOREIGN PATENTS 739,752 Great Britain Nov. 2, 1955 OTHER REFERENCES Hassler: Active Carbon, pp. 277-282, Chemical Publishing 00., Brooklyn, N.Y., 1951 

11.PROCESS FOR REPRODUCING LONG-DISTANCE FUEL GAS, WHICH COMPRISES COOLING HOT CRUDE FUEL GAS HIGH IN CARBON MONOXIDE AND ATTENDANT IMPURITIES OBTAINED BY PRESSURE GASIFICATION OF SOLID CARBON-CONTAINING FUELS WITH STEAM AND OXYGEN TO A TEMPERATURE OF 190 TO 210*C. BY CONTACTING THE SAME UNDER PRESSURE WITH A MEMBER SELECTED FROM THE GROUP CONSISTING OF STEAM, OIL TAR, AND MIXTURES THEREOF, WHEREBY THE HIGH BOILING PRODUCTS, REACTIVE ASPHALTIC MATERIALS, RESIN-FORMING IMPURITIES, WATER, TARS, PITCHES, AND LIKE MATERIALS FORM A CONDENSATE, CONDUCTING THE CRUDE GAS AFTER SEPARATION THEREFROM OF SAID CONDENSATE AT THE CONVERSION TEMPERATURE AND AT SUBSTANTIALLY THE SAME PRESSURE AS THE PRESSURE OF THE STARTING HOT CRUDE GAS OVER A CONVERSION CATALYST TO THEREBY CONVERT THE HIGH CONTENT OF CARBON OMNOXIDE AND STEAM UNUSED IN THE PRESSURE GASIFICATION CONTAINED IN SAID CRUDE GAS TO CARBON DIOXIDE AND HYDROGEN, RECOVERING THE LOW CARBON MONOXIDE CONTENT FUEL GAS, THEREAFTER COOLING AND SCRUBBING THE CONVERTED GAS TO REMOVE THEREFROM FURTHER IMPURITIES SSUCH AS HYDROGEN SULFIDE, ORGANIC SULFUR COMPOUNDS, AMMONIA, HYDROCYANIC ACID AND NITRIC ACID, ADMIXING SAID PURIFIED GAS WITH GASES HAVING HIGHER CALORIFIC VALUES THAN SUCH PURIFIED GAS TO THEREBY FORM A LONG-DISTANCE FUEL GAS HAVING A CONDENSATE BELOW THAT OF COKE OVEN GAS. 